Re: Apparent Bug in Nmap

[David Fifield <david () bamsoftware com>]

On Thu, Jun 04, 2009 at 11:38:03AM -0500, sbammel wrote:
> The following is relevant data for that which appears clear to me is a
> bug in Nmap.  Thanks for a fine program.
>
> Test #1: (gives correct results)
>
> Nmap Command:
> c:\Temp\nmap>nmap -sP 10.11.0.1 10.11.0.2
> Starting Nmap 4.85BETA9 ( http://nmap.org ) at 2009-06-04 11:19 Central Daylight Time
> Nmap done: 2 IP addresses (0 hosts up) scanned in 5.14 seconds
>
> Ethereal Output:
> No.     Time        Source                Destination           Protocol Info
>       1 0.000000    10.10.0.81            10.11.0.2             TCP      51666 > http [ACK] Seq=0 Ack=0 Win=2048 Len=0
>       2 0.004446    10.10.0.81            10.11.0.1             TCP      51666 > http [ACK] Seq=0 Ack=0 Win=1024 Len=0
>       3 0.004644    10.10.0.81            10.11.0.1             ICMP     Echo (ping) request
>       4 0.013672    10.11.0.1             10.10.0.81            ICMP     Destination unreachable (Host unreachable)
>       5 0.014266    10.11.0.1             10.10.0.81            ICMP     Destination unreachable (Host unreachable)
>       6 2.028412    10.10.0.81            10.11.0.1             ICMP     Echo (ping) request
>       7 2.028776    10.11.0.1             10.10.0.81            ICMP     Destination unreachable (Host unreachable)
>       8 2.029244    10.10.0.81            10.11.0.1             TCP      51667 > http [ACK] Seq=0 Ack=0 Win=4096 Len=0
>       9 2.029571    10.11.0.1             10.10.0.81            ICMP     Destination unreachable (Host unreachable)
>
>
> Test #2: (shows 10.11.0.1 up when it is not)
>
> Nmap Command:
> c:\Temp\nmap>nmap -sP 10.11.0.2 10.11.0.1
> Starting Nmap 4.85BETA9 ( http://nmap.org ) at 2009-06-04 11:19 Central Daylight Time
> Host 10.11.0.1 is up (0.00s latency).
> Nmap done: 2 IP addresses (1 host up) scanned in 1.74 seconds
>
> Ethereal Output:
> No.     Time        Source                Destination           Protocol Info
>      10 11.277806   10.10.0.81            10.11.0.1             TCP      62969 > http [ACK] Seq=0 Ack=0 Win=3072 Len=0
>      11 11.278167   10.11.0.1             10.10.0.81            ICMP     Destination unreachable (Host unreachable)
>      12 11.278961   10.10.0.81            10.11.0.2             TCP      62969 > http [ACK] Seq=0 Ack=0 Win=2048 Len=0
>      13 11.279236   10.10.0.81            10.11.0.2             ICMP     Echo (ping) request
>
>
> The order of the IP addresses makes a difference in the results.  

I don't have an explanation for why the order of targets would matter.
In test #1, Nmap should have taken any one of the host unreachables sent
by 10.11.0.1 as evidence that the host was up.

Please send the output of these commands:
nmap -d3 -sP 10.11.0.1 10.11.0.2 > test-1.txt
nmap -d3 -sP 10.11.0.2 10.11.0.1 > test-2.txt

David Fifield

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